Efeitos do manejo sobre os atributos físicos de um latossolo vermelho-amarelo distrófico, em Poto Velho - RO

Abstract

Understanding and quantifying the impact of land use and management on physical quality is critical to the development of sustainable agricultural systems. Thus, the objective of this work was to evaluate the effect of gypsum, soil scarification and crop succession systems on the physical attributes of a Red - Yellow Dystrophic Latosol in Porto Velho - RO. The experiment was implemented in the agricultural year 2013, crop 2014, in an area in the experimental field of Embrapa Rondônia, the area was cultivated with Brachiaria brizantha cv. Marandú during eighteen years (1990 to 2008), after this period of cultivation with Braquiaria, was kept in fallow for four years (2009 to 2013), when the experiment was installed. The treatments consisted in the absence and addition of 2000 kg ha-1 of agricultural gypsum, absence and presence of soil scarification, and three crop succession systems: SP (soybean / fallow), SMP (soybean / corn / fallow) and SMBP (soybean / corn / brachiaria / fallow). The experimental design was in randomized blocks, arranged in a 2x2x3 factorial scheme with eight blocks. Four years after the installation of the experiment trenches were opened and soil samples were collected in the layers of (0.00 - 0.05, 0.05 - 0.10 and 0.10 - 0.20 m). With the aid of volumetric rings, soil samples were collected for determination of macroporosity, microporosity, total porosity, soil density, soil moisture and penetration resistance. Blocks with preserved structure were manually collected and defragmented in aggregates. With the aid of sieves, aggregates with a diameter of between 8 and 4.75 mm were separated for stability analysis of aggregates in water. The hypothesis of normality of the data was tested by the Shapiro-Wilk test, and subjected to analysis of variance (ANOVA). When the significance test was found, the means were compared by the Scott-Knott test at the 5% of probability. Crop succession systems may influence soil physical characteristics, and the best aggregate stability values were observed in the SMBP and SMP succession systems, which, in addition to preserving the aggregate structure, allowed a reduction in RP.